Certain processes for the production of a dinitrile product such as a fumaronitrile or maleonitrile product are known. One, for example, involves oxydehydrogenation.
Kosel et al., U.S. Pat. No. 3,313,840 (1967), disclose a catalytic oxydehydrogenation process for the production of fumaro- and maleonitrile from succinonitrile. The process must be carried out in the presence of at least one oxide which is stable at the reaction temperature of an element of Groups Vb or VIb of the Periodic system, especially vanadium pentoxide, molybdenum trioxide and, particularly, chromium (III) oxide. It is disclosed that the dinitriles are produced in a practically constant ratio of fumaronitrile to maleonitrile of 5:4. A problem with this process can be the frequent regeneration or replacement of the catalyst.
Other processes for the production of a dinitrile product such as a fumaronitrile or maleonitrile product are also known. They generally fall into seven representative types.
The first is dehydration of a diamide of fumaric or maleic acids with phosphorous pentoxide such as taught by Pace, U.S. Pat. No. 2,438,019 (1948). Problems with this include difficulty in synthesizing the reactant diamide and the practical control of the strict reaction conditions.
The second is a 1,2-diiodoethylene and copper cyanide reaction such as taught by Hochwalt, U.S. Pat. No. 2,399,349 (1946). A problem with this is the procurement of special starting materials.
The third is an acetonitrile high temperature dehydrogenation-dimerization with chlorine such as taught by Japanese Patent Publication No. 17965/1967. Problems with this include the practical control of the strict reaction conditions and the corrosive nature of the reaction.
The fourth is a cyanoacetylene and prussic acid reaction such as taught by Morita et al., U.S. Pat. No. 3,959,345 (1976). A problem with this is the procurement of starting materials.
The fifth is oxycyanation, which is a 3-cyano-1-propene and cyanide reaction in the presence of oxygen such as taught by Kominomi et al., Kogyo Kogaku Zasshi, 74, 2464-68 (1971). Problems with this include low selectivity and catalyst coking.
The sixth is a fumaronitrile preparation by a chloro-acrylonitrile and aqueous alkali or alkaline earth cyanide reaction such as taught by Mowry et al., U.S. Pat. No. 2,471,767 (1949). A problem with this is procurement of starting materials and strict reaction conditions.
The seventh is ammoxidation, a process involving an unsaturated compound, ammonia and oxygen. Proposed unsaturated compounds include benzene, cyclohexene, phenol and butadiene such as disclosed by Furuoya et al., U.S. Pat. No. 4,436,671 (1984). Problems with this include production of by-products such as acrylonitrile, acetonitrile and prussic acid.
In addition, the foregoing processes are typically restricted to preparing narrow classes of products, often only the compounds fumaronitrile and maleonitrile. Most are not readily commercially adaptable.
What is lacking and what is needed is a process for preparing a dinitrile product which is simple and direct, a process in which selectivity can be varied by varying process parameters and a process which may prepare a wide variety of dinitriles including, for example, fumaro- and maleonitriles. What is also lacking and what is needed is such a process which may be readily commercializable.